Gear parts in wind turbines, such as gear parts in yaw systems or gear parts in pitch systems, normally comprise a toothed rim arranged to engage with a toothed rim of another gear part during operation. Sometimes one or more of the teeth of the toothed rim become damaged, and it is necessary to repair or replace the gear part. Replacing the gear part is undesirable, since this is very expensive, and may require that large components of the wind turbine are dismantled in order to allow the damaged gear part to be removed and a new gear part to be installed.
As an alternative, the damaged gear part may be repaired on site, i.e. without removing the damaged gear part from the wind turbine. U.S. Pat. No. 8,287,238 B2 discloses a method for repairing a hub pitch gear assembly. The method includes providing a ring assembly for adjusting a pitch angle of a wind turbine blade having a plurality of gear teeth. A segment of the ring assembly is removed, e.g. through milling, the segment including at least a portion of at least one gear tooth, to form a repair cavity. A repair segment configured to mate the repair cavity is provided and the repair segment is directed into the repair cavity and fastened in position.